1. Field of the Invention
The present invention relates to an optical measurement carbon substrate that is suitable for mounting thereon a specimen such as a powder, biological molecules, or the like, for observation in a reflected light optical system.
A substrate for a DNA chip, in which a DNA fragment is fixed to the substrate and, when making measurements, a fluorescence-marked DNA sample is applied thereon for observation under various kinds of microscopes, also falls within this category.
2. Description of the Related Art
In the fields of material sciences and some of life sciences, a specimen such as a powder, biological molecules, or the like, is illuminated through an objective lens, and the reflected light, scattered light, fluorescence, or the like from the specimen is brought to a focus for observation. Various kinds of microscopes using reflected light optics (reflected light illumination) are used (examples include a differential interference contrast microscope, polarized light microscope, an interference microscope, a fluorescence microscope, a confocal microscope, a phase contrast microscope, a near-field optical microscope, and an evanescent microscope). In this case, the specimen to be observed is placed on a slide glass originally designed for observation with transmitted light illumination. If such a slide glass is used for observation in a reflected light optical system, reflections of the slide glass itself, auto fluorescence, etc. become a problem.
In reflected light optical systems, there is no need to place a specimen on a light transmitting substrate such as a slide glass. One possible approach here is to place a specimen for observation, not on a slide glass, but on an opaque plate whose reflections and auto fluorescence are reduced to extremely low levels.
Japanese Unexamined Patent Publication No. 2003-121438 discloses that an amorphous carbon plate, obtained by carbonizing a resin molding by calcination, is used as a substrate for a DNA chip in which a DNA fragment is fixed to the substrate.
When using an opaque material for an optical measurement substrate, it is required that the substrate has an extremely flat surface free from irregularities of micron order so as not to cause a problem for microscope observation. If a substrate plate obtained by calcining a molded resin plate is to be used as an optical measurement substrate, the surface of the plate must be ground flat, but in the case of a plate made only of amorphous carbon (glassy carbon), the surface is extremely hard and is therefore difficult to grind, the resulting problem being that the processing cost, to obtain the required flatness, increases.